1. Field of the Invention
The present invention relates to mechanical grippers, and, more particularly, to the synchronization and braking of jaw tooling for such grippers.
2. Description of the Related Art
Grippers are mechanical devices characterized by one or more jaws that are moved together or apart by motive means such as an electric motor or pneumatic piston. Generally, the jaws of the gripper are attached to tooling that is responsible for transferring the force of the gripper to a workpiece such that the workpiece may then be held, moved, and/or rotated. This tooling may need to grasp workpieces that differ from one another in size, shape, draft, material, mass, etc. It is often desirable for the movements of the jaws to be synchronized together so that the gripped workpiece is always moved to a repeatable position coincident with the middle of the gripper, irrespective of which jaw might contact the surface of the workpiece first. Methods used in prior art to synchronize jaw motion include racks driving a common pinion, as disclosed in U.S. Pat. No. 7,490,881, or pinned linkages, as disclosed in U.S. Pat. No. 6,598,918. However, such methods used in the prior art to synchronize jaw motion result in an undesirable increase in the physical size, weight, and manufacturing cost of the gripper.
The loss of power, and thereby a loss of grip force, is continually a safety concern, irrespective of whether a gripper is powered pneumatically or with an electric motor. If power is lost while the gripper is in operation and gripping a workpiece, the resulting loss of grip force may lead to the possibility of a falling object. To prevent damage to the workpiece, the surroundings, or harm to an operator, a braking or clamping device can be implemented to prevent the jaws of the gripper from moving apart and dropping the workpiece. In the prior art, brakes or clamping mechanisms have been physically located exterior to the envelope of the jaws and base plate of the gripper. Yet, the exterior location creates the undesirable effect of increasing the volume occupied by the gripper.
What is needed in the art is a gripper that is cost effective and provides an augmented synchronization of jaw motion and a reduction of risk in dropping the workpiece in the event of a loss of power or compressed air supply.